Then one day Field took a bottle of prescription pills and ended up in a psychiatric lockdown.

"I felt like a child all over again," Field said. "I felt like the first day I went to kindergarten and I didn't want to leave home. And I wanted to go someplace and just hide, because it was too much to take."

Midlife Triggers

Field isn't alone in her struggle. Experts say between 1 million and 3 million middle-aged women in this country have anorexia or bulimia. One out of every 10 eating disorder patients is over 40.

Doctors say specific "midlife events" are the triggers.

"They've experienced the divorce, the death of a parent or both parents, a traumatic illness like breast cancer, children leaving home," said Dr. Ed Cumella of the Remuda Ranch Center for Anorexia and Bulimia in Wickenburg, Ariz. "Any woman with low self-esteem who has gone through that kind of life stressor is at risk."

Field experienced a number of those triggers -- a sick relative, children on the verge of leaving home, and fears of turning 40. She spent three months in rehab, and today she feels as close to cured as she's ever going to get.

"I may never view myself physically in the same way that other people do. I'm always going to be supercritical," she said.

"But I'm alive and I'm vibrant. I have hope. I have things that I want to do," she added. "I still have time. I still have life ahead of me."

Dieters and Anorexics

There's a big difference between a woman who wants to lose a little weight and a woman with anorexia, said ABC News Medical Contributor Dr. David Katz.

"There's an obsessive element to an eating disorder," he said. "The person becomes completely preoccupied with their weight, their activity pattern, their diet. It's not just something they're doing to lose a little weight."

"The underlying issues are about mental health, no question about that. It's not about nutrition or diet per se," he added.

Whether the anorexic patient is a teenager or a middle-aged woman, the treatment runs a similar course of psychotherapy, Katz said.

"In general, this is about control," he said. "You see someone who is struggling to get control over her life."

Older patients can often be better patients, because unlike a reluctant teenager who is dragged in by her parents, the adult patient brings herself in and wants to be there, he said.